1. Field of the Disclosure
The present invention relates generally to power converters. More specifically, examples of the present invention are related to switching power converters that utilize an error amplifier in a feedback loop to regulate an output.
2. Background
Many electronic devices such as cell phones, laptop computers, etc., use direct current (dc) power to operate. Conventional wall outlets generally deliver a high voltage alternating current (ac) power that needs to be transformed to dc power in order to be used as a power source by most electronic devices. Switched mode power supplies are commonly used due to their high efficiency, small size, and low weight to convert the high voltage ac power to a regulated dc power. In operation, a switch is used to provide a desired output by either switching at a variable duty ratio (typically the ratio of on-time of the switch to total switching period) or by varying the number of ON and OFF cycles per unit time.
A switched mode power supply also employs a controller, which typically provides output regulation by sensing the output and controlling the switch in a closed loop. The controller may receive a feedback signal representative of the output and then vary one of the control parameters (such as for example duty ratio, or for example the number of ON and OFF cycles of the switch per unit time) in response to the feedback signal to regulate the output of the power supply to a desired quantity.
One practical consideration in the design of a controller is the accuracy with which the feedback signal represents the output of the power supply. This is because as the feedback signal tracks the output of the power supply with less deviation from the ideal value, the controller can react with greater accuracy to the changes at the output, which then results in tighter output regulation.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.